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Frictional Resistance

The frictional resistance R🇫 of the hull depends on the size of the hull’s wetted area AS, and on the specific frictional resistance coefficient CF. The friction increases with fouling of the
hull, i.e. by the growth of, i.a. algae, seagrass, and barnacles.
An attempt to avoid fouling is made by the use of antifouling hull paints to prevent the hull from becoming “longhaired”, i.e. these paints reduce the possibility of the hull becoming fouled by living organisms. The paints containing TBT (tributyltin) as their principal biocide, which is very toxic, have dominated the market for decades, but the IMO ban of TBT for new applications from 1 January 2003, and a full ban from 1 January 2008, may involve the use of new (and maybe not as effective) alternatives, probably copper-based antifouling paints.
When the ship is propelled through the water, the frictional resistance increases at a rate that is virtually equal to the square of the vessel’s speed.

Frictional resistance represents a considerable part of the ship’s resistance, often some 70-90% of the ship’s total resistance for low-speed ships (bulk carriers and tankers), and sometimes less than 40% for high-speed ships (cruise liners and passenger ships). 

The frictional resistance is found as follows:

R🇫 = C🇫 × K

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